Question

app运行没有错误，我想计算距离，当我点击按钮开始它将是开始位置，当点击重置 - 完成位置，它将计算开始和结束之间的距离位置，但它无法计算距离和速度。怎么纠正？这是我的代码：

public class Tab1 extends Fragment implements LocationListener, View.OnClickListener{

GoogleMap googleMap;
SupportMapFragment mapFragment;
private Button buttonStart;
private Button buttonStop;
private Button buttonReset;
private Chronometer chronometerRun;
private double latStart;
private double lonStart;
private double latStop;
private double lonStop;
private LatLng latLngStart;
private LatLng latLngStop;
private TextView textViewDistance;
Location location;
long time = 0;

@Nullable
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
   View view = inflater.inflate(R.layout.tab_1, container, false);

    textViewDistance = (TextView)view.findViewById(R.id.textViewDistance);
    buttonStart = (Button) view.findViewById(R.id.buttonStart);
    buttonStop = (Button) view.findViewById(R.id.buttonStop);
    buttonReset = (Button) view.findViewById(R.id.buttonReset);
    chronometerRun = (Chronometer) view.findViewById(R.id.chronometerRunning);

    buttonStart.setOnClickListener(this);
    buttonStop.setOnClickListener(this);
    buttonReset.setOnClickListener(this);

    initMap();
    return view;
}

public void initMap(){

    if (googleMap == null) {
        mapFragment = (SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map);

    }

    googleMap = mapFragment.getMap();
    googleMap.setMyLocationEnabled(true);
    // Getting LocationManager object from System Service LOCATION_SERVICE
    LocationManager locationManager = (LocationManager) getActivity().getSystemService(Context.LOCATION_SERVICE);
    // Creating a criteria object to retrieve provider
    Criteria criteria = new Criteria();
    // Getting the name of the best provider
    String provider = locationManager.getBestProvider(criteria, true);
    // Getting Current Location
    location = locationManager.getLastKnownLocation(provider);
    if(location!=null){
        onLocationChanged(location);
    }
    locationManager.requestLocationUpdates(provider, 20000, 0, this);
    googleMap.getUiSettings().setMyLocationButtonEnabled(true);

}

public double CalculationByDistance(LatLng StartP, LatLng EndP) {
    int Radius = 6371;// radius of earth in Km
    double lat1 = StartP.latitude;
    double lat2 = EndP.latitude;
    double lon1 = StartP.longitude;
    double lon2 = EndP.longitude;
    double dLat = Math.toRadians(lat2 - lat1);
    double dLon = Math.toRadians(lon2 - lon1);
    double a = Math.sin(dLat / 2) * Math.sin(dLat / 2)
            + Math.cos(Math.toRadians(lat1))
            * Math.cos(Math.toRadians(lat2)) * Math.sin(dLon / 2)
            * Math.sin(dLon / 2);
    double c = 2 * Math.asin(Math.sqrt(a));
    double valueResult = Radius * c;
    double km = valueResult / 1;
    DecimalFormat newFormat = new DecimalFormat("####");
    int kmInDec = Integer.valueOf(newFormat.format(km));
    double meter = valueResult % 1000;
    int meterInDec = Integer.valueOf(newFormat.format(meter));
    Log.i("Radius Value", "" + valueResult + "   KM  " + kmInDec
            + " Meter   " + meterInDec);

   return Radius * c; //km

}



@Override
public void onClick(View v)
{
    switch(v.getId())
    {
        case R.id.buttonStart:
            chronometerRun.setBase(SystemClock.elapsedRealtime() - time);
            chronometerRun.start();
            latStart = location.getLatitude();
            // Getting longitude
            lonStart = location.getLongitude();
            Toast.makeText(Tab1.super.getActivity() , "latStart: "+latStart+"; lonStart: "+lonStart,Toast.LENGTH_LONG).show();
            // Creating a LatLng object
            latLngStart = new LatLng(latStart, lonStart);
            Log.i("latStart: "+latStart , "lonStart: "+lonStart);
            break;
        case  R.id.buttonStop:
            time = SystemClock.elapsedRealtime() - chronometerRun.getBase();
            chronometerRun.stop();

            break;
        case R.id.buttonReset:
            time = SystemClock.elapsedRealtime() - chronometerRun.getBase();
            Toast.makeText(Tab1.super.getActivity() , "Time: "+time,Toast.LENGTH_SHORT).show();

            latStop = location.getLatitude();
            // Getting longitude of the current location
            lonStop = location.getLongitude();
            Toast.makeText(Tab1.super.getActivity() , "latStop:  "+latStop+"; lonStop: "+lonStop,Toast.LENGTH_LONG).show();
            // Creating a LatLng object for the current location
            latLngStop = new LatLng(latStop, lonStop);
            Log.i("latStop: "+latStop , "lonStop: "+lonStop);
            double distance = CalculationByDistance(latLngStart,latLngStop);
            String sDistance = Double.toString(distance);
            textViewDistance.setText(sDistance);
            if (time > 0 ) {
                double speed = distance / time*1000; // time in ms
                Toast.makeText(Tab1.super.getActivity() ,  "Distance: "+ distance +"; Speed: "+speed,Toast.LENGTH_LONG).show(); }
            time = 0;
            chronometerRun.setBase(SystemClock.elapsedRealtime());
            chronometerRun.stop();
            break;
    }
}

@Override
public void onLocationChanged(Location location) {
    // Getting latitude of the current location
    double latitude = location.getLatitude();
    // Getting longitude of the current location
    double longitude = location.getLongitude();
    // Creating a LatLng object for the current location
    LatLng latLng = new LatLng(latitude, longitude);
    // Showing the current location in Google Map
    googleMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
    // Zoom in the Google Map
    googleMap.animateCamera(CameraUpdateFactory.zoomTo(14));
}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) {

}

@Override
public void onProviderEnabled(String provider) {

}

@Override
public void onProviderDisabled(String provider) {

}
}

Answer 1

你不必像这样自己调用onLocationChanged方法，每次位置发生变化时都会自动调用它。您必须在重置按钮代码中再次调用getLastKNownLocation并将该位置作为最后一个位置（就像在init映射中那样）或者在onLocationChanged方法中更新自身的全局变量。所以（伪伪代码）：

onLocationChanged(Location location)
{
   globalVarLocation.latitude = location.latitude;
   globalVarLocation.longitude = location.longitude;
}

应用程序不计算android的距离和速度

1 个答案: